The invention relates to materials used in the fabrication of structural members or trim elements used in construction materials and fenestration units installed in residential and commercial architecture. More particularly, the invention relates to an improved profile or structural member that can be used as a direct replacement for wood and metal components having superior properties for fenestration, structural or construction purposes. The structural members of the invention can comprise sized lumber replacements and structural components with complex functional shapes such as wood and door rails, jambs, stiles, sills, tracks, stop and sash and miscellaneous trim elements. Further, the invention relates to structural components used in the fabrication of fenestration units such as windows and doors for commercial and residential architecture.
The structural components are made from an extruded composite polymer foam material. The structural components of the invention can form high strength joints in the construction assembly. The materials can be easily installed, adjusted, shimmed and trimmed with conventional fasteners and techniques. The components have thermal and mechanical properties rendering them durable yet easy to manufacture and install.
Conventional industrial, commercial and residential architecture commonly involve the use of structural and nonstructural components in the assembly of useful units. Such components are often made from concrete, stone, wood, glass or metal. These materials are well known and are well understood in their applicability to construction purposes.
Wood has been milled into shaped structural components such as sized lumber, trim. post and beam and have also been used to form structural components that can be assembled with glass to form door and window units. Wood, lumber, trim. post, beam and assembled units comprising wood have obvious utility and are well adapted for many uses in many residential or commercial installations. However, the wood used in these applications, under certain circumstances, can have problems. Wood can deteriorate due to the effect of fungus and insect attack. Further, wood members also suffer from cost problems related to the availability of suitable for wood for construction purposes and require substantial upkeep comprising painting or staining. Metal, typically aluminum or steel, components are also often used in industrial, commercial and residential construction. Metal components can suffer from rust or corrosion problems and require their own particular construction skills and maintenance regimen. Vinyl polymeric materials have also been used in formation of structural members and for forming profiles in window and door assembly. Such vinyl materials typically comprise a major proportion of a vinyl polymer with a variety of additive materials that are used. Filled and unfilled (filled with additive materials such as fiber, inorganics, dye etc.) rigid and flexible thermoplastic materials have been extruded or injection molded into a variety of both structural and sealing materials. A thermoplastic polyvinyl chloride has been combined with wood members in the manufacture of PERMASHIELD(copyright) brand windows manufactured by Andersen Corporation for many years. This vinyl cladding technology is disclosed in Zaninni, U.S. Pat. Nos. 2,926,729 and 3,432,885. The technology disclosed in these patents involves the extrusion or injection molding of a thin polyvinyl chloride coating or envelope loosely formed around a shaped wooden structural member.
The polyvinyl chloride thermoplastic materials have also been combined with wood products to make extrusion materials. Initial efforts resulted in a material that can be directly extruded to form a member that has a modulus typically about 500,000 or less. Such members also failed to have adequate compressive strength, coefficient of thermal expansion, coefficient of elasticity, fastener retention or other useful properties required for use in many construction applications.
More recently, U.S. Pat. Nos. 5,486,553, 5,539,027, 5,406,768, 5,497,594, 5,441,801 and 5,518,677 assigned to Andersen Corporation, disclose the use of a thermoplastic such as polyvinyl chloride and wood fiber for the purpose of manufacturing a high strength composite material in the FIBREX(copyright) brand materials technology. Such composites are useful in the manufacture of a structural member such as a hollow profile that can be used in window and door manufacture. These materials have a high modulus (800,000 psi or more) and can be easily manufactured, assembled and installed. These unique high strength materials have had substantial success with respect to their use in window and door manufacture.
The PERMASHIELD(copyright) brand technology and the FIBREX(copyright) brand materials technology have substantial utility and have had substantial success in a variety of applications. Further extensions of thermoplastic polymer technology are useful for other applications. A need exists to obtain materials having enhanced properties.
We have found that a superior structural foamed material can be used to form a member which can be used as a replacement for stone, wood, glass and metal members. The member comprise a thermoplastic foam comprising a foamed composite comprising a thermoplastic polymer and a wood fiber. The wood fiber can be derived from either soft woods or evergreens or from hard woods commonly known as broad leaf deciduous trees. Soft woods are generally preferred for fiber manufacture because the resulting fibers are longer, contain high percentages of lignin and lower percentages of hemicellulose than hard woods. Additional fiber make-up can be derived from a number of secondary or fiber reclaim sources including bamboo, rice, sugar cane, and recycled fibers from newspapers, boxes, computer printouts, etc. One preferred source of wood fiber of this invention comprises the wood fiber product or by-product of sawing or milling soft woods. A quality fiber can be made by milling and a by-product of milling commonly known as sawdust or milling tailings can be used.
A large variety of thermoplastic polymer or resins can be used in the foamed composite materials of the invention. For the purpose of this application, a useful resin is a general term covering a thermoplastic that may or may not contain an additional filler or reinforcing material, other than wood fiber, that have mechanical, chemical and thermal properties suitable for use as structural components, machine components and chemical processing equipment components. We have found that the resins useful in the invention include both condensation polymeric materials and vinyl polymeric materials. The foamed material can provide improved thermal and physical properties. A large variety of vinyl polymeric materials can be used in the composite materials can be used in the composite materials of the invention. Useful vinyl polymers are polymers made by homopolymerization, copolymerization or terpolymerization methods. Condensation polymer resins can also be used in the composite materials of the invention.
The properties enhanced in the foamed composite include resistance to shrinkage, and improved COTE(Coefficient Of Thermal Expansion), compressive strength and fastener retention. Such a material display properties rendering the structural member ideal for industrial, commercial and household construction applications. The materials have acceptable thermal properties including a minimal coefficient of thermal expansion, minimal shrink and minimal heat distortion. Further, the materials can be easily manufactured, assembled into a useful structure and can be easily installed. For the purpose of this patent application the term xe2x80x9cextrusion massxe2x80x9d indicates material processed by an extruder resulting in the foamed thermal plastic wood fiber composite. The extrusion mass can comprise a blend of powder, flaked or pelletized thermoplastic discrete wood fibers and a separate blowing agent each component mixed together to form a final extrusion mass. Alternatively, the extrusion mass can comprise a preformed pellet comprising thermoplastic, wood fiber and blowing agent preformed and a preextruded in a pellet composition. Alternatively, the extrusion mass can comprise a thermoplastic wood fiber pellet dry blended with a blowing agent. Alternatively, the extrusion mass can comprise the thermoplastic with the blowing agent dissolved or dispersed in the thermoplastic in the form of a pellet which is then blended with a separate wood fiber phase. In other words, the extrusion mass can comprise the thermoplastic, the wood fiber or the blowing agent in any useful form of an extrudable mass.